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Carbs n stuff

Discussion in 'Triumph (Classic)' started by Fast Eddie, Apr 3, 2017.

  1. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Been a while since I was playing with 650 upwards Triumph twins. When I was, general consensus was that 30mm carbs were only for girls, 32s were popular, as was boring out mk1 carbs to 33.5mm, and guys running mk2s ran all sorts of sizes right up to 38mm.

    What's the thinking these days for a fast fun road bike? I can't help thinking that 30mm was probably fine all along!!
     
  2. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    30 mm Mk1 Amals don't appear to be restrictive on a roadgoing 650 Triumph.
     
  3. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I reckon you're about right there TT...
     
  4. xbacksideslider

    xbacksideslider VIP MEMBER

    Joined:
    Aug 19, 2010
    The “cork” in a Triumph head likely is not a 30mm carb.
     
  5. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Well, that depends which other corks you’ve removed first!

    As you’ve already discovered John, the first cork is probably those cigar silencers.

    Then what, in a T140 it’s probably the exhaust cam?

    I’ve got a pair of Hyde half race cams on the shelf that keeping talking to me, whispering temptations into my gullible ear...
     
  6. Hillbilly Bike

    Hillbilly Bike

    Joined:
    Oct 18, 2018
    One cork is the large and poorly shaped ports on later T120 heads..Raising the intake port floor and slight enlarging the port roof can add noticable power...
    T140 can be improved with an earlier 3134 type exhaust cam and moving the intake cam timing to 100 degrees center line..Certianly something to be gained with a proper exhaust system...Lots of opinions on what that is..
     
    xbacksideslider likes this.
  7. xbacksideslider

    xbacksideslider VIP MEMBER

    Joined:
    Aug 19, 2010
    Hmmm. What’s the T140’s stock intake cam centerline? And, short of splitting cases, what’s to be gained by adjusting the intake cam’s centerline by itself?
     

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